Smiths Station climate

Smiths Station Frost Dates and Growing Season

NOAA 1991-2020 normals for Mulberry Grove, 8 km from Smiths Station, elevation 501 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Mulberry Grove. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around March 21 and the first fall freeze around November 18, a growing season of about 243 days.

Median at 36°F
last April 5, first November 5
Median at 32°F
last March 21, first November 18
Median at 28°F
last March 3, first December 1

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FApr 21Apr 16Apr 11Apr 8Apr 5Apr 2Mar 29Mar 24Mar 15
32°FApr 13Apr 4Mar 31Mar 26Mar 21Mar 16Mar 11Mar 3Feb 25
28°FApr 2Mar 22Mar 15Mar 10Mar 3Feb 28Feb 22Feb 15Feb 3
24°FMar 21Mar 7Feb 28Feb 21Feb 14Feb 7Feb 1Jan 27Jan 16
20°FMar 7Feb 25Feb 13Feb 6Jan 31Jan 26Jan 19Jan 12Dec 31
16°FFeb 26Feb 10Feb 3Jan 30Jan 24Jan 19Jan 15Jan 8Dec 30

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FOct 23Oct 28Nov 1Nov 3Nov 5Nov 8Nov 12Nov 16Nov 21
32°FNov 1Nov 5Nov 9Nov 14Nov 18Nov 22Nov 26Dec 1Dec 5
28°FNov 8Nov 17Nov 22Nov 28Dec 1Dec 5Dec 10Dec 17Dec 25
24°FNov 25Dec 2Dec 8Dec 14Dec 21Dec 27Jan 1Jan 7Jan 19
20°FDec 9Dec 18Dec 26Jan 1Jan 5Jan 11Jan 16Jan 23Feb 4
16°FDec 23Jan 1Jan 6Jan 10Jan 15Jan 21Jan 28Feb 2Feb 14

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F243233228222216212206201192
32°F271262254249243237230223214
28°F306294286279272266258248237
24°F340328320312305297289280264
20°F365365351341333325317306293
16°F365365365365365358346334322

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
99% of years
20°F or colder
80% of years
16°F or colder
43% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
2,275
Cooling degree days, base 65°F
2,051
Growing degree days, base 40°F
8,970
Growing degree days, base 45°F
7,276
Growing degree days, base 50°F
5,712
Growing degree days, base 55°F
4,312
Growing degree days, base 60°F
3,085

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January574168
February419291
March27616234
April11652390
May18196643
June0381831
July0484949
August0477942
September3323769
October71103499
November29115206
December507289

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 8 km from Smiths Station. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00096148 (Mulberry Grove). Public domain.